lassa fever case study
TRANSCRIPT
Lassa Fever Case Study
Njala University
Thomas Winnebah
Bashiru Koroma
Morrison Lahai
Alie Kamara
Alhaji Gogra
John Borway
Institute of Development Studies
Melissa Leach
Annie Wilkinson
Catherine Grant
Tulane University
Lina Moses
Kenema Government Hospital
Donald Grant
James Koninga
Lansana Kanneh
Franklyn Kanneh
Momoh Foday
Special thanks to the communities of
Lalehun Kovoma
Lambayama (Kenema)
Largo Square (Segbwema)
Majihun
Lassa Fever
• Viral hemorrhagic fever endemic to West Africa
• Mortality up to 69% Kenema Government Hospital, Sierra Leone (Shaffer et al. 2014 PLoS NTD)
• Rodent reservoir: Mastomys natalensis
• Where and how are people getting
infected?• West African subspecies
(Redding et al. 2016 Mol Ecol Evol)
• Rodent to human transmission: 80%
(Lo Iocono et al. 2015 PLoS NTD)
Photo: Dan Bausch
Photo: Lina Moses
Image: David Redding
Lassa Fever Case Study
• Land use impact on small mammal abundance, M. natalensis
• Livelihood practices and ecosystems service uses that increase/decrease exposure to M. natalensis
• Virus regulation as an ecosystems service (human and rodent infection)
• Local knowledge of disease transmission and prevention
Lambayama Section, Kenema
Majihun Lalehun Kovoma
Largo Square Section, Segbwema
Spatial Dimensions
Lalehun Kovoma
OC
T
NO
V
DEC
JAN
FEB
MA
R
AP
R
MA
Y
JUN
JUL
AU
G
SEP
OC
T
NO
V
DEC
JAN
Har
vest
Bu
rnin
g
Bru
shin
g
Pla
nti
ng
Upland Cycle
2 years of data collection
2013 2014 2015
FEB
MA
R
AP
R
MA
Y
JUN
JUL
AU
G
Four points of data collection
Tran
sect
map
pin
gFo
cus
gro
up
sTr
app
ing
Blo
od
sam
plin
g
Focu
s gr
ou
ps
Trap
pin
gB
loo
d s
amp
ling
Focu
s gr
ou
ps
Trap
pin
gB
loo
d s
amp
ling
Trap
pin
g
Swamp Cycle
Wee
din
g,
bir
d m
gmt
Wee
din
g,
bir
d m
gmt
Har
vest
Har
vest
Har
vest
Veg
etab
le
gard
enin
g
Soil
pre
p,
pla
nti
ng
Veg
etab
le
gard
enin
g
Soil
pre
p,
pla
nti
ng
Bu
rnin
g
Bru
shin
g
Pla
nti
ng
EBOLA
Temporal Dimensions
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
OctNov 13 FebMar 14 MayJ 14 AugS 15
Cleared
Old fallow
Swamp rice
Upland mixed
Young fallow
Total
Mastomys Trap Success by Land Use and Season
Fallow land recently cleared for upland mixed crops
Swamp vegetable, post rice harvest
Upland soil prep, planting
Oct 2013 Mar 2014 May 2014 Aug 2015
Fallow land recently cleared—Feb/March
Men: convert bush to farm—brushing, felling trees, burning; use of tools, fireWomen and children: feed work parties, bring food and water, gather and bundle fuel wood
Swamp Vegetable Garden, post rice harvest—Feb/March
Women: Vegetable gardening using hands intensively. Independent income source.
Upland Soil Preparation and Planting—May
Women, men and children all involved in planting rice, ground nuts, intercrops. Land (and burrows?) significantly disturbed
Seasonal Peaks of Lassa Fever cases reporting to Kenema Government Hospital 2008-2012
Peak of M. natalensisabundance in cleared and swamp land
Peak of M. natalensisabundance in upland farms
(Shaffer et al. 2014, PLoS NTD)
This study also showed Lassa fever for women
Analyses in Progress
• Human Lassa Antibody Seroconversions• Gender and age distribution• Association with agricultural activities
• Integrating data on local understanding of rodent, diseases, and their control
• Virus incidence in small mammal populations• Species richness, disease regulation• Interspecific competition
Key findings• Peak abundance of Mastomys coincides with
times of significant human-driven land
perturbation
• This perturbation is gender and age specific.
• This coincides with peak seasons in Lassa fever incidence• Seroconversion data will give better insight
• Lassa fever disease system should be examined in the context of ecosystems services• Mastomys as protein source
• Mastomys as agricultural pest and disease reservoir
• Potential cross-cutting with agricultural sector
This work, Dynamic Drivers of Disease in Africa Consortium, NERC project numberNE-J001570-1, was funded with support from the Ecosystem Services for Poverty Alleviation (ESPA)programme. The ESPA programme is funded by the Department for International Development (DFID), theEconomic and Social Research Council (ESRC) and the Natural Environment Research Council (NERC).